A material exhibiting a negative Poissons ratio is always one of the leading topics in materials science, which is due to the potential applications in those special areas such as defence and medicine. In this letter, we demonstrate a new material, few-layer orthorhombic arsenic, also possesses the negative Poissons ratio. For monolayer arsenic, the negative Poissons ratio is predicted to be around -0.09, originated from the hinge-like structure within the single layer of arsenic. When the layer increases, the negative Poissons ratio becomes more negative and finally approaches the limit at four-layer, which is very close to the bulks value of -0.12. The underlying mechanism is proposed for this layer-dependent negative Poissons ratio, where the internal bond lengths as well as the normal Poissons ratio within layer play a key role. The study like ours sheds new light on the physics of negative Poissons ratio in those hinge-like nano-materials.
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